Problem: Evaluate the following expression when $b = 7$ and $a = 5$. $4$ $b$ $ + 7$ $a$ $ - 8$
Solution: Substitute $7$ for ${b}$ and $5$ for ${a}$ $ = 4{(7)} + 7{(5)} - 8 $ $ = 28 + 35 - 8 $ $ = 55$